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16
votes
4answers
8k views

Removing control chars (including console codes / colours) from script output

I can use the "script" command to record an interactive session at the command line. However, this includes all control characters and colour codes. I can remove control characters (like backspace) ...
14
votes
5answers
9k views

How to clear terminal completely?

When we use clear command or Ctrl+L in terminal, it clears terminal but we can still scroll back to view the last used commands. Is there a way to completely clear the terminal?
13
votes
4answers
692 views

Is there any reason why I get ^[[A when I press up arrow at the console login screen?

Whenever I'm at the console login, I press up arrow intentionally to see the previously typed commands. But I see this ^[[A. But when I press Ctrl Alt Print Screen Scroll Lock Pause Break Page Up ...
12
votes
2answers
2k views

How to avoid escape sequence attacks in terminals?

Reading the details of CVE-2009-4487 (which is about the danger of escape sequences in log files) I am a bit surprised. To quote CVE-2009-4487: nginx 0.7.64 writes data to a log file without ...
12
votes
2answers
2k views

Where do my ANSI escape codes go when I pipe to another process? Can I keep them?

I sometime want to pipe the color-coded output fror a process, eg. grep... but when I pipe it to another process, eg. sed, the color codes are lost... Is the some way to keep thes codes intact ? ...
9
votes
2answers
6k views

inline double and single quote escaping

I'm having trouble with escaping characters in bash. I'd like to escape single and double quotes while running a command under a different user. For the purposes of this question let's say I want to ...
8
votes
4answers
6k views

How to make the terminal display user@machine in bold letters?

I have seen in some screen-shots (can't remember where on the web) that the terminal can display the [username@machine /]$ in bold letters. I'm looking forward to getting this too because I always ...
8
votes
2answers
2k views

How do I background an SSH session? [duplicate]

Possible Duplicate: How can I break away from an SSH session that has crashed? I have started an SSH session on the command line, but now I want to get back to my local command line. For ...
7
votes
4answers
4k views

How can I create a file with multiple lines from the command-line?

How can I enter the following contents in a file: Hi abcd I tried using echo "Hi\nabcd" >> ab.txt, but in the file it's written as is (the \n is included, instead of a newline)
6
votes
3answers
2k views

Escape sequences with “echo -e” in different shells

I just noticed that it seems like the flag -e does not exist for the echo command in my shell on Linux. Is this just a messed up setting or is it "normal"? Some code as an example: #!/bin/sh echo -e ...
6
votes
1answer
529 views

Escape sequences in output of script called from ncurses application

I'm currently running mcabber as my Jabber client (which uses ncurses) in a tmux session on my homeserver. Locally i run iTerm2 as a terminal emulator, which supports the triggering of growl ...
5
votes
3answers
2k views

Where do I find a list of terminal key codes to remap shortcuts in bash?

For example: "\e[1;5C" "\e[Z" "\e-1\C-i" I only know bits and pieces, like \e stands for escape and C- for Ctrl, but what are these numbers (1) and letters (Z)? What are the ;, [ and - signs for? ...
5
votes
1answer
607 views

Why do I have to escape a “dot” twice?

I know that we can escape a special character like *(){}$ with \ so as to be considered literals. For example \* or \$ But in case of . I have to do it twice, like \\. otherwise it is considered ...
5
votes
2answers
2k views

Why does Ctrl-D (EOF) exit the shell?

Are you literally "ending a file" by inputting this escape sequence, i.e. is the interactive shell session is seen as a real file stream by the shell, like any other file stream? If so, which file? ...
5
votes
1answer
3k views

Trouble in script with spaces in filename

I've got a script that scp's a file from remote host back to local. Sometimes the file names contain spaces. scp does not like spaces in its file names. For some reason my attempts at handling the ...
5
votes
1answer
2k views

In Bash, why is PROMPT_COMMAND set to something invisible?

On RHEL6 and CentOS 6, /etc/bashrc sets PROMPT_COMMAND here: case $TERM in xterm*) if [ -e /etc/sysconfig/bash-prompt-xterm ]; then PROMPT_COMMAND=/etc/sysconfig/bash-prompt-xterm ...
5
votes
1answer
3k views

export HTTP_PROXY and special characters in passwd

Suppose for the sake of argument my password below is abc123@ I need to authenticate my linux machine through a corporate proxy to get patches and updates... normally I'd use this: export ...
5
votes
2answers
3k views

Change colors in console/virtual terminal

Is there a way to alter all the available colors in console / virtual terminal? By console, I mean what you get after pressing CTRL + ALT + F1 and not anything like xterm or urxvt. So, I guess that ...
5
votes
2answers
137 views

Escape code 50 in xterm

My coworker has the following in the ~/.bash_profile of many of our servers: echo -e "\033]50;SetProfile=Production\a" The text doesn't seem to matter, since this also works: echo -e ...
5
votes
2answers
712 views

is it possible to send a control sequence to a terminal emulator using the keyboard

If you type echo -e '\eZ' and hit return in a shell running in an xterm, you'll see that the terminal emulator prints an obscure code 1;2c. This seems to indicate that xterm interprets the VT100 ...
4
votes
5answers
308 views

How to use ' in alias?

I have one-line that I want to call using alias. while printf '%s ' "$(df -P / | awk 'NR==2 { print $(NF-1) }')"; do sleep 30; done I tried to escape ' like \' but it didn't work. What is the ...
4
votes
1answer
1k views

How can I match the page break character in a regular expression?

Nano calls it ^L, but of course, typing something like $ grep -v "^\^L" file doesn't work. Its unicode codepoint is 000C. How can I match it in a regular expression?
4
votes
1answer
566 views

Reverse control-code look up for terminals

My understanding is that terminals often use ANSI control-codes to represent non-alphanumeric character sequences. For example, when editing .inputrc for Bash in Linux, it's easy to find code ...
4
votes
2answers
233 views

The difference between \e and ^[

Gilles wrote: character 27 = 033 = 0x1b = ^[ = \e Demizey wrote: ^[ is just a representation of ESCAPE and \e is interpreted as an actual ESCAPE character Then I also found this line from ...
4
votes
1answer
89 views

how to escape “\”in ssh-copy-id?

I'm connected to Ubuntu server that is a member of a corporate Active Directory domain via likewise-open. The users are in the form mydomain\myuser. I can connect to it via ssh, escaping the \ with ...
4
votes
2answers
301 views

Is there a way to lock terminal's title?

Sometimes there're lots of different sessions opened in own terminal's tabs and it's rather desirable to have theirs initial titles (named by session name) locked since local title tweaks make those ...
4
votes
1answer
564 views

Re-escape brackets in PS1

As others have pointed out, color codes in PS1 should be bracketed by \[ and \] to avoid them taking up horizontal space. I've added the necessary code to .bashrc: highlight() { if [ -x ...
4
votes
2answers
327 views

DEC ANSI command sequence questions; cursor movement

So I'm writing a terminal emulation (I know, I should just compile putty, etc.) and am at the stage of plodding through vttest to make sure it's right. I'm basing it on the VT102 for now but will add ...
3
votes
5answers
521 views

What are the special characters to print from a script to move the cursor?

I found that by printing \r from a script the cursor moves to the beginning of the line. What character will move the cursor up one line? Where is a list of these special characters? EDIT: Working ...
3
votes
2answers
2k views

Passing a bash command-line argument containing a dot

How can a command-line argument containing a dot (.) be passed? Are there any escape sequences for capturing characters like dot? The following invocation of a bash-script from the shell does not ...
3
votes
2answers
361 views

Unix Shell and colours

Can any one please help me understand this code snippet that I found in .profile file echo -en "\e[32;44m $(hostname) \e[m";echo -e "\e[m"
3
votes
3answers
5k views

How can I pass strings with single quotes to grep?

My desired outcome is the following: to recursively search a directory looking for a given string in all found files. The following command is my usual port of call: find ./ | xargs grep -ns 'foobar' ...
3
votes
1answer
277 views

Could someone please explain some of these escape codes?

I'm seeing this in my .bashrc file: PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\ [\033[01;34m\]\w\[\033[00m\]\$ ' and I have absolutely no idea what all those ...
3
votes
2answers
2k views

How to escape < or > in a parameter in shell?

I'd like to use grep with a PCRE expression that contains the < character. Bash thinks I want to redirect, but I don't want to. How can I escape <?
3
votes
2answers
1k views

Trying to print up down arrow keys

I have this: I read down arrow key abc@abc-ubuntu:~/bashpratice$ read -n 3 key ^[[Babc@abc-ubuntu:~/bashpratice$ I am able to grep for it abc@abc-ubuntu:~/bashpratice$ echo $key | grep '\[' [B ...
3
votes
1answer
178 views

How to find out the escape sequence my keyboards sends to terminal?

Let's say we have a generic keyboard with some unknown keys which may send escape sequences to terminal. The keyboard is connected to an xterm terminal emulator running on a generic BSD/Linux. To ...
3
votes
2answers
133 views

Can I make grep treat escaped multiline as a single line?

How can I make tools like grep treat multilines escaped with a backslash as a long single line? Let's say I have some files that looks like this: testvar=test1 \ test2 \ test3 ...
3
votes
1answer
44 views

How do I generate the sequence “\e[Z” in a terminal?

It is bound to menu-complete in GNU readline. $ bind -p|grep menu "\e[Z": menu-complete # menu-complete-backward (not bound) # old-menu-complete (not bound) I think it's Meta-something.
3
votes
1answer
1k views

How to bypass GNOME Terminal when sending keyboard input?

When running an interactive shell application, how can I send it a key (or key combination) which would normally be intercepted by GNOME Terminal? In this particular instance it's the F10 key which is ...
3
votes
2answers
88 views

How to change font colors in terminal?

I know how to change the font color via preferences, but it changes the color of ALL text, as in below:     What I'm going for is something more like this:     Any ...
3
votes
1answer
492 views

Printing colored text using script

When I type below command in the shell I get the OUTPUT in green color. Command echo "\033[32mCONNECTING TO abpwrk\033[m"; Output(in green color) CONNECTING TO abpwrk But if I use the same ...
3
votes
1answer
1k views

Escaping of meta characters in basic/extended posix regex strings in grep

Is it possible to escape all meta characters of a string inside a variable before passing it to grep? I know similar question has been asked before on SE (here) and also a good explanation here, but I ...
3
votes
0answers
168 views

How to create a bash command which creates output that exactly mimics a source text file that can be pasted into bash shell where histexpand is on?

The goal is to create a bash one line command that can be copied and pasted - for instance published on a web forum - and then patches files. See it as a way to distribute a patch file by copy and ...
2
votes
2answers
595 views

How to copy a piped list of files contained spaces and apostrophes?

I have a list of files generated using find that I want to feed (pipe) to cp. My problem is that the files have spaces and apostrophes in them, leading cp to repeatedly complain that it "cannot stat". ...
2
votes
2answers
212 views

Maximize xterm via bash script

I have found this answer providing how to manipulate the current xterm window's dimensions, ie: echo -ne "\e[8;30;30t" How can I modify this to maximize the window (xterm's alt + enter shortcut)? ...
2
votes
1answer
107 views

What characters TAR doesn't like?

I keep a list of photos burned to dvds for incremental backups but I got into a strange situation where a file was already burned into a dvd but tar keeps saying it's not. Here the steps to reproduce: ...
2
votes
2answers
53 views

Meaning of backslash

Why the following command prints Smith but not \Smith? echo \Smith
2
votes
2answers
96 views

What is the problem with the output of plink?

On my Windows7 machine, I'm traversing to the installed path of PuTTy Application and running: plink <hostname> to connect to my remote Linux host. I see some unrecognized characters in the ...
2
votes
1answer
295 views

How to capture text formatting in bash?

The following shell script works but removes colored formatting generated by rspec: #!/bin/bash OUTPUT=`rspec` echo "$OUTPUT" How to preserve the colors?
2
votes
1answer
318 views

highlighting text in shell

I have always been using below method to highlight background of text in shell . tput smso;printf " TEXT ";tput rmso; How can I achieve the same thing without using tput( I mean some way formatting ...